Understanding Shutter Speeds And ƒ-stops. Here are some tips to help you get consistently good exposure
By Rick Sammon
Shutter Speed Basics Let’s begin with shutter speed. Shutter speed is the time the shutter, which lets light onto the digital image sensor, remains open—or the time the image sensor is activated. If you’re new to photography, look at it this way. If you’re in a room and open and lower a window shade, you’re basically doing the same thing a shutter does: letting light expose an area. The longer you leave the shade up, the longer the room is illuminated.
Knowing which speed to choose is the key to getting a desired effect. Sometimes it’s an educated guess. Sometimes it’s just plain luck. But most of the time, it should be the result of knowing how different shutter speeds affect subject movement.
Fast shutter speeds “freeze” action, as did a 1/500th second shutter speed when I photographed this horse and rider at the Double JJ Ranch in Rothbury, Mich. The faster the shutter speed, the better chance you have of freezing the action. But there’s more. Telephoto lenses (above 100mm), exaggerate handheld camera shake, as binoculars exaggerate hand movement. So, you need a fast shutter speed to freeze your movement, too. A tripod, other camera support or an Image Stabilization lens can also help reduce camera shake. Tech Info: Canon 1D Mark II, Canon 100-400 IS lens @ 400mm, ISO 400, 1/500th sec. @ ƒ/5.6.